Blender Video Sequence editor taking all memory and crashing
Blender include a setting in the User Preferences/System tab to limit the amount of memory that the Video Sequence Editor can use. This setting should be never set to more than your available system memory plus the available swap - otherwise Blender can attempt to grab more memory than is available and cause the system to crash or become unresponsive. 

At the bottom of the System tab in User Preferences is a 'Sequencer/Clip Editor' setting that dictates the memory limit for blender when caching and rendering videos in the VSE. This setting normally defaults to 1024Mb - ie, 1Gb - and so should not cause a problem (unless your system has less than 1Gb of available memory). If this is set to a value that is larger than your system memory - or less than your 'free' memory when Blender is not running - then you may get Blender trying to allocate more memory than is available.

Reduce the value to limit the amount of memory available to Blender.